reactive barrier is definitely better with a shield.
There's no "reactive barrier". You mean Deflective Barrier or Reactive Armor? Deflective barrier actually requires a shield, so yes, its better with one
investing in armor buffing skills and armor restore skills is a must (Geo and Hydro respectively).
Hydro on a warrior? Seems like a waste. If you get the Five-Star Diner talent, you can replenish 30% of your total vitality by eating a single dinner for 1AP! This restores even more than the Huge Healing potion, and yes, MUCH more than the Hydro HP spells like Restoration or Healing Ritual even at Hydro 10. You shouldn't need any healing spells on your warrior, just chug those dinners, which are very cheap to make too (raw meat/fish + fire). And if you also get the Living Armor talent, any heals will also restore your magic armor.
